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142                         METALLURGY OF IRON AND STEEL.
large quantities of pig-iron. At Steelton we have antedated all others in America in the regular use both of melted and cold pig-iron as the full charge in a basic furnace, for we began using melted pig-iron directly from the blast furnace in 1891, it being recognized at the time that we were merely repeating what had been done a generation ago across the water. Three years later we ran two or more 50-ton furnaces on cold pig-iron without scrap, and from time to time^ as the limited supply of iron for distribution to trie Bessemer and open hearth would allow, we used the iron in a melted state. It was from about 1896 that melted iron was regularly and continuously taken from the blast furnaces to the open-hearth plant, from two to four 50-ton furnaces having been run regularly in that manner from then until now.
This has been done before, and is done elsewhere, but it is believed that nowhere else has iron been worked directly from the blast furnace without the use of a receiver, with silicon varying from 0.50 up to 3 per cent, and with no prohibitory trouble from frothing or from loss of time. This trouble is avoided by the ability to tip the furnace and prevent the metal and slag from flowing out of the doors on the front side, there being no doors on the tap-hole side, the excess of slag being provided for by holes left in the bottom of the port opening. Any hole or runner in a door or in the side of the furnace gives trouble from the chilling of the slag if the stream is small, and if the stream is large there is pretty certain to be some metal lost through the opening, but by having the opening located in the port, at the joint between the fixed end and the rotating portion, the opening is exposed continually to the flame passing over it in either direction and the slag has no chance to cool. If it should solidify, the crust can be broken by moving the furnace in either direction, thereby tearing apart the slag and starting the stream again. It is in this manner that the practice has been carried on at Steelton, and the melters soon learned without instructions to keep the furnaces partly tipped over throughout the whole period of the violent frothing, thereby rendering possible the rapid addition of ore.
(8) In an article on tilting furnaces by A. P. Head* he states that one of the objections to tilting furnaces is this:
"The inlet of cold air during pouring tends to oxidize the man-
* Journal L and S.t Vol. 1899.